A technique for a vehicle to detect a distance to an approaching vehicle approaching the vehicle by using an obstacle sensor mounted on the vehicle has heretofore been known.
For example in Japanese Patent Application Publication No. 2010-30514, a braking force is applied to the vehicle when the distance between the vehicle and the approaching vehicle is shortened to a predetermined braking control activation distance or less, and the braking control activation distance is set according to an angle formed by a travel direction of the vehicle and an extending direction of a road along which the approaching vehicle is running.